i have a 1995 audi a6 and about a week ago my engine started shaking while i was driving i felt it throughout the whole car. when i doing around 10- 20 mph i would feel it the most once i hit around 40 it went away. Now it doesn't happen until i hit 60 so i try and stay below that. can someone give me an idea of whats going on or what i need to replace/fix thanks